What is the bolt that is at the bottom of the front exhaust?

Not the 2 spring bolts or the 3 connectors to the headers, There is one large bolt as well. I installed new headers along with the front exhaust pipe. Everything connected perfectly. But as I drove I heard a sound of metal clanking. Obviously a bolt was loose somewhere. By the time I got to work I heard it pop out under the car and now where I think I didn't tighten the bolt, it's gone. So now exhaust comes out from there. I just want to replace that bolt but can't figure out what it is called or where to get it.

If this helps, Google "97 civic bolton
premiere headers"
I got the one from auto part
warehouse. In the photo you can see
that in the front end that starts to go
under the car, there is a bolt at the
end of the pipe. It is right before the
2 spring bolts. In the photo it's
already attached. I didn't tighten it
and that's what came off and is
causing the leak.

Sorry dude I was away..now I went looking and did the Google search you posted but all I found, and after looking a lot, was pictures like this, do you have Photoshop or anything like it, and point out what part? Or post the picture you are talking about.... I'm lost...

I figured it out. Thank you very much
though.
Apparently my car needs 2 O2
sensors. In that photo you put up, the
pipe in the right has an open
thread/hole for another 02 sensor.
It's to give better fuel economy but
doesn't give a check engine light
(this is only because when I took off
the last exhaust system, there wasn't
one already there) I searched and the
solution is actually a M18x1.5 bolt.
Found it at Toyota dealership as an
old oil drain plug. Same size so I'm
just going to plug it with that rather
then put a new sensor.
Thanks again

I'm looking for a cheap bolt on muffler for my 2012 Honda Civic LX. The closest I could
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